<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<h1 id="h1">你好，你好</h1>
		<h1>你好，你好</h1>
		<h1>你好，你好</h1>
		
		
	</body>
	<script>
		var h1 = document.getElementById("h1");
		h1.onclick = function(){
			alert("点击h1")
		}
		document.write('<h2>世界</h2>')
	</script>
</html>
